Lost Asteroid - 21st Century

21st Century

2007 WD5 is a 50 m (160 ft) Apollo-class near-Earth object and a Mars-crosser asteroid discovered on 20 November 2007 by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD₅ caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance of colliding with Mars on 30 January 2008. However, by 9 January 2008 additional observations allowed NASA's Near Earth Object Program (NEOP) to reduce the uncertainty region resulting in only a 1-in-10,000 chance of impact. 2007 WD₅ most likely passed Mars at a distance of 6.5 Mars radii. Due to this relatively small distance and the uncertainty level of the prior observations, the gravitational effects of Mars on its trajectory are unknown and, according to Steven Chesley of NASA's Jet Propulsion Laboratory Near Earth Object program, 2007 WD₅ is currently considered "lost". The best fit trajectory had the asteroid passing within 21,000 km of Mars and only 16,000 km from the moon Deimos.

In the search for various types of near-Earth object, such as quasi-satellites and Earth-crosser asteroids, objects that may correspond to some lost sightings include 2006 RH₁₂₀ or 3753 Cruithne, among others.

In 2007, the object 2007 RR9 was found to be the asteroid 6344 P-L, lost since 1960. It is a potentially hazardous object and probably a dormant comet, although it was not visibly outgassing at that time.